When the bearings on my old semi-float rear axle went, the whole axle/wheel assembly silently pulled out of the housing. It didn't just make a lot of noise and come to a slow, grinding stop. Luckily I was in town, travelling at slow speeds and was flagged down by a pedestrian.
And yes, the truck had been overloaded (heavily? probably) for a couple years before hand. It was one of those "an xtra leaf in the spring pack will fix that" deals back when I was young and ignorant.
Since then I've been much more worried when exceeding a truck's rear GAWR.